1. Field of the Invention
The present invention relates to a shifting apparatus for shifting a front derailleur or rear derailleur of a bicycle. More particularly, the invention relates to an improvement in a shifting apparatus for a bicycle having an indicator for indicating speed stages of a derailleur.
2. Description of the Related Art
A conventional shifting apparatus of the type noted above is disclosed in Japanese Utility Model Publication Kokai No. 1990-68289, for example. As does the apparatus disclosed in this publication, many of the conventional shifting apparatus include a control cable takeup element rotatably mounted on a fixed shaft, and a speed indicator having a rotatable member also rotatably mounted on the fixed shaft. The rotatable member is rotatable with the takeup element to indicate speed stages of a derailleur.
U.S. Pat. No. 5,325,735 discloses another example of shifting apparatus which is mounted adjacent a handlebar. This apparatus includes a lever pivotable about a rotational axis of a takeup element, and an indicator rotatable about an axis disposed at 90 degrees to the above rotational axis. The takeup element and indicator are interlocked through crown gears.
U.S. Pat. No. 4,325,267 discloses a further example of shifting apparatus which is mounted on a handlebar. A lever usually is arranged pivotable about an axis extending perpendicular to the handlebar axis or a mounting plane of the shifting apparatus. In the apparatus disclosed in this patent, however, the lever is pivotable about an axis inclined with respect to the usual pivotal axis of the lever in order to allow a thumb and a finger of the cyclist's hand holding the handlebar to follow the lever with ease during a shifting operation.
In the first known example of shifting apparatus noted above, the takeup element and the rotatable member of the indicator are rotatably mounted on one fixed shaft, to realize a compact construction. However, when this shifting apparatus is attached to the handlebar with a shift lever disposed in a position easy to operate to rotate the takeup element, the operability of the lever is improved indeed but the indicator lies in a position difficult for the cyclist to see. There is room for improvement in this respect.
In the second known example noted above, the pivotal axis of the lever extends perpendicular to the rotational axis of the indicator. Thus, compared with the first example, the cyclist has a good view of the indicator with the operability of the lever maintained when effecting a shifting operation. However, the indicator disposed at 90 degrees to the handlebar axis (or the mounting plane of the apparatus) has a surface always extending parallel to the handlebar axis (or the mounting plane of the apparatus). When the shifting apparatus is mounted so that the shift lever lies in an optimal position for the cyclist, the indicator does not necessarily lie in an optimal position to be viewed by the cyclist. There is room for improvement in this respect. Further, since the rotational axis of the indicator is disposed at 90 degrees to the handlebar axis, an interlock mechanism (e.g. meshing of crown gears as disclosed) is provided between the takeup element and indicator. This results in an increased number of components and a complicated construction. Thus, there is room for improvement from the points of view of cost and assembling trouble.
In the third known example noted above, the shifting apparatus has a pivotal axis of the lever inclined at a predetermined angle to the handlebar. This apparatus may be set to an optimal condition for the cyclist to operate the shift lever. However, since the indicator is rotatable about the inclined pivotal axis of the shift lever, the display plane of the indicator in the above set condition does not necessarily lie in an optimal position to be viewed by the cyclist. There is room for improvement in this respect.
Besides the known examples described above, a further type of apparatus is known which includes an indicator, a takeup element and a shift lever formed separately from one another, the indicator being disposed in a position easy to see, with the shift lever disposed in a position easy to operate. However, naturally such an apparatus has a complicated construction. The shifting apparatus is costly as a whole.